Calcium base alloy



Patented Nov. 12, 1940 UNITED STATES CALCIUM BASE ALLOY Charles E. Nelson and Lawrence B. Otis, Midland, Mich., assignors to The Dow Chemical Company, Midland, Michigan Mich., a corporation of No Drawing. Application October 25, 1939,

Serial No; 301,169

2 Claims.

The invention relates to calcium base alloys and more particularly concerns calcium base alloys containing magnesium.

Metallic calcium has recently been finding in- 5 dustrial application in various fields. As an illustration it has been found to be particularly valuable as a deoxidizer of copper because the resulting metal has a very high electrical conductivity. It is also useful as a deoxidizer of steel and in the purification of nickel, lead, and

the like. However,- calcium metal has never enjoyed extensive use in the above industries mainly because of the fact that it is difficult to handle and store for any length of time due to its reactivity in air. For example, if calcium metal is stored, it deteriorates rapidly due to the formation of a surface coating of hydroxide or oxide which is not self-healing thus causing the metal to entirely disintegrate eventually.

It is, therefore, an object of this invention to provide a calcium base alloy which will serve as a source of calcium having a high resistivity to oxidation corrosion so that it may be stored over long periods of time without any appre 25 ciable deterioration occurring.

We have found that by adding from about 18 to 23 per cent, and preferably from 20 to 22 per cent of magnesium to calcium, an alloy is obtained that has a much greater resistance to 80 oxidation in air than that of pure calcium metal.

The proportion of magnesium should be maintained fairly closely within the above limits since the presence of more or less magnesium in the alloy produces an alloy of highly inferior corro- 86 sion characteristics. As an illustration of the superior corrosion characteristics of alloys having the above composition, a calcium alloy was made up containing about 20 per cent magnesium and stored for over a year. After this time it 10 was observed that no appreciable surface oxidation or deterioration had taken place. On the other hand pure calcium stored under similar conditions completely disintegrated in a much shorter period of time. Ithas been found that calcium cleaned by sand blasting one day will on the next day be so covered with a film of calcium oxide as to be unusable until it is again cleaned.

Alloys of the above composition can be readily produced by adding the necessary amount of clean, substantially pure calcium to molten magnesium with stirring while protecting the surface of the molten metals with natural gas or 10 I other inert protective gases or by means of a suitable flux. It is preferable to add the calcium to the molten magnesium since the temperature required is much lower than where the metals are alloyed in the reverse order. The lower tem- 15 perature is of course an advantage since calcium exhibits the tendency to burn or oxidize rapidly at higher temperatures, as, for example, around its melting point.

Alloys of the above composition may be stored 20 for long periods of time and furnish a convenient source of calcium in connection with its use as a deoxidizer of copper, steel, and the like, and for many other uses wherein the presence of a relatively small proportion of magnesium 25 is not detrimental.

Other modes of applying the principle of our invention may be employed instead of thine explained, change being made as regards the ingredients and the steps herein disclosed, provided those stated by any of the following claims or their equivalent be employed.

We therefore particularly point out and distinctly claim as our invention:

1. A calcium base alloy containing from about 18 to 23 per cent magnesium, the balance being, calcium.

2. A calcium base alloy containing from 20 to 22 per centmagnesium, the balance being calcium.

CHARLES E. NELSON. LAWRENCE B. OTIS. 

